KR102053138B1 - Solar cell - Google Patents

Abstract

Solar cell according to an embodiment of the present invention, the photoelectric conversion unit; And first and second electrodes connected to the photoelectric converter. The first electrode may include a bus electrode including at least one finger electrode including a plurality of finger electrode parts, a main part formed in a direction crossing the plurality of finger electrode parts, and a protruding part protruding from the main part. Include. The protruding portion is formed over at least two of the plurality of finger electrode portions.

Description

Solar cell {SOLAR CELL}

The present invention relates to a solar cell, and more particularly, to a solar cell having an improved electrode structure.

Recently, with the anticipation of depletion of existing energy sources such as oil and coal, there is increasing interest in alternative energy to replace them. Among them, solar cells are in the spotlight as next generation cells for converting solar energy into electrical energy.

Solar cells include various layers, electrodes, etc., formed on a substrate, depending on the design. Adjacent solar cells are electrically connected to each other by ribbons connected to busbar electrodes. However, disconnection may occur in a portion of the finger electrode connected to the busbar electrode adjacent to the portion where the ribbon is attached due to an alignment error or a difference in width between the ribbon and the busbar electrode. In addition, the contact area between the ribbon and the busbar electrode may decrease due to the alignment error. As a result, the output and reliability of the solar cell module may be reduced.

The present invention seeks to provide a solar cell having high efficiency and reliability.

Solar cell according to an embodiment of the present invention, the photoelectric conversion unit; And first and second electrodes connected to the photoelectric converter. The first electrode may include a bus electrode including at least one finger electrode including a plurality of finger electrode parts, a main part formed in a direction crossing the plurality of finger electrode parts, and a protruding part protruding from the main part. Include. The protruding portion is formed over at least two of the plurality of finger electrode portions.

The protruding length of the protruding portion may be smaller than the width of the main portion.

Protruding length of the protruding portion may be 0.1mm to 0.7mm.

The protrusion may have a width of 2 mm to 10 mm.

The protruding portion may be formed over two to ten of the plurality of finger electrode portions.

The bus bar electrode may have a width of 2.1 mm to 3.4 mm at the protruding portion.

The protruding portion may include an end protruding portion located at an end of the main portion.

The end protrusion may be symmetrically positioned at both sides with respect to the main part.

The ribbon may further include a ribbon connected to the first electrode, and the ribbon may have one end positioned above the busbar electrode, and the other side may extend to a neighboring solar cell. The end protrusion may include a first end protrusion adjacent to the one end and a second end protrusion positioned at a position opposite to the first end protrusion. The width of the first end protrusion may be equal to or longer than the width of the second end protrusion.

The protruding portion may further include a central protrusion protruding from an inner region of the main portion.

The protruding length of the central protrusion may be smaller than the protruding length of the end protrusion.

The central protrusion and the end protrusion may be regularly arranged with a uniform gap therebetween.

The bus bar electrode may further include a ribbon connected to the first electrode, and a width of the bus bar electrode may be greater than a width of the ribbon at a portion where the protruding portion is disposed.

Width of the ribbon: the width ratio of the busbar electrode at a portion where the main portion is located may be 1: 0.80 to 1: 1.22.

The finger electrode may further include an alignment mark part formed in a direction intersecting the finger electrode part at a position corresponding to an outer portion of the protruding portion.

The photoelectric conversion unit may include a semiconductor substrate and an emitter region. The solar cell may further include an insulating layer formed on the emitter region. The finger electrode may be formed through the insulating layer to contact the emitter region, and the bus bar electrode may be formed on the insulating layer.

The finger electrode may have a two-layer structure including a first layer positioned on the photoelectric converter and a second layer positioned on the first layer. The busbar electrode may have a single layer structure having the same material and thickness as the second layer.

The first layer and the second layer may have different materials.

Further comprising a ribbon connected to the second electrode, the second electrode may have a larger width than the ribbon as a whole.

Solar cell according to another embodiment of the present invention, the photoelectric conversion unit; And first and second electrodes connected to the photoelectric converter. The first electrode may include a finger electrode including a plurality of finger electrode portions, and a bus bar electrode including at least one main portion formed in a direction crossing the plurality of finger electrodes and a protruding portion protruding from the main portion. do. The busbar electrode has a width of 2.1 mm to 3.4 mm at the protruding portion.

In this embodiment, even if a misalignment of the ribbon occurs, including a protruding portion where the busbar electrode protrudes from the main portion, the drop in contact area between the busbar electrode and the ribbon can be compensated for, and the emitter region and the anti-reflection film caused by the ribbon can be compensated. And damage to the finger electrode and the like can be prevented. Thereby, the fall of the output of a solar cell module can be prevented and reliability can be improved.

1 is an exploded perspective view of a solar cell module including a solar cell according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of the solar cell module taken along line II-II of FIG. 1.
3 is a partial cross-sectional view of a solar cell according to an embodiment of the present invention.
4 is a front plan view of a solar cell according to an embodiment of the present invention.
FIG. 5 is a front plan view illustrating a first layer and a second layer constituting the first electrode of FIG. 4.
6 is a rear plan view of a solar cell according to an embodiment of the present invention.
7 is a front plan view showing a solar cell according to another embodiment of the present invention.
8 is a front plan view showing a solar cell according to another embodiment of the present invention.
9 is a front plan view showing a solar cell according to another embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention; However, the present invention is not limited to these embodiments and may be modified in various forms.

In the drawings, illustrations of parts not related to the description are omitted in order to clearly and briefly describe the present invention, and the same reference numerals are used for the same or extremely similar parts throughout the specification. In the drawings, the thickness, the width, and the like are enlarged or reduced in order to clarify the description. The thickness, the width, and the like of the present invention are not limited to those shown in the drawings.

And when any part of the specification "includes" other parts, unless otherwise stated, other parts are not excluded, and may further include other parts. In addition, when a part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the case where the other part is "just above" but also the other part located in the middle. When parts such as layers, films, regions, plates, etc. are "just above" another part, it means that no other part is located in the middle.

Hereinafter, a solar cell according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is an exploded perspective view of a solar cell module including a solar cell according to an embodiment of the present invention, Figure 2 is a schematic cross-sectional view of the solar cell module cut along the line II-II of FIG.

1 and 2, a solar cell module 100 according to an embodiment of the present invention may include a solar cell 150, a front substrate 210 and a solar cell positioned on a front surface of the solar cell 150. 150 may include a back sheet 220 positioned on the back surface. In addition, the solar cell module 100 may include a first sealant 131 between the solar cell 150 and the front substrate 210 and a second sealant 132 between the solar cell 150 and the rear sheet 220. It may include.

First, the solar cell 150 is a semiconductor device that converts solar energy into electrical energy, for example, a silicon solar cell, a compound semiconductor solar cell, a tandem solar cell cell), a dye-sensitized solar cell, and the like.

This solar cell 150 includes a ribbon 142. Adjacent solar cells 150 may be electrically connected in series, in parallel or in parallel by the ribbon 142. Specifically, the ribbon 142 includes a first electrode (see reference numeral 24 of FIG. 3) formed on the front surface of the solar cell 150, and a second electrode (FIG. 3) formed on the rear surface of another adjacent solar cell 150. Refer to 34). That is, when the ribbon 142 is extended from the front of one solar cell 150 to the rear of the other solar cell 150 and then thermally compressed, the two solar cells 150 are connected by the ribbon 142. Can be. In this manner, the plurality of solar cells 150 may be connected.

The ribbon 142 may be made of various materials having excellent electrical properties and excellent physical properties. For example, the ribbon 142 may include a soldering material, and may include Sn / Ag / Cu-based, Sn / Ag / Pb-based, Sn / Ag-based, and Sn / Pb-based materials. Or, it may include a metal material (for example, aluminum) of excellent conductivity. Alternatively, the ribbon 142 may be formed by stacking an anti-oxidation film on a solder material. However, the present invention is not limited thereto.

In the detailed description, the term ribbon 142 is used, but the present invention is not limited thereto. That is, the ribbon 142 may include not only a soldering material but also a structure connecting the solar cells 150 by various structures.

In addition, the bus ribbon 145 alternately connects both ends of one row connected by the ribbon 42. The bus ribbon 145 may be disposed in a direction crossing the ends of the solar cells 150 forming one row. The bus ribbon 145 is connected to a junction box (not shown) that collects electricity produced by the solar cell 150 and prevents electricity from flowing back.

The first sealing material 131 may be located at the front surface of the solar cell 150, and the second sealing material 132 may be located at the rear surface of the solar cell 150. The first sealing member 131 and the second sealing member 132 are bonded by lamination to block moisture or oxygen that may adversely affect the solar cell 150, and to allow each element of the solar cell to chemically bond. do.

The first sealing material 131 and the second sealing material 132 may be an ethylene vinyl acetate copolymer resin (EVA), polyvinyl butyral, silicon resin, ester resin, olefin resin and the like. However, the present invention is not limited thereto. Accordingly, the first and second seal members 131 and 132 may be formed by other methods other than lamination using various other materials.

The front substrate 210 is positioned on the first sealing member 131 so as to transmit sunlight, and is preferably tempered glass in order to protect the solar cell 150 from an external impact or the like. In addition, it is more preferable that it is a low iron tempered glass containing less iron in order to prevent reflection of sunlight and increase the transmittance of sunlight.

The back sheet 220 is a layer that protects the solar cell 150 from the back side of the solar cell 150, and functions as a waterproof, insulation, and UV protection. The back sheet 220 may be a TPT (Tedlar / PET / Tedlar) type, but is not limited thereto. In addition, the rear sheet 220 may be made of a material having excellent reflectivity so that the solar sheet incident from the front substrate 210 side can be reflected and reused. However, the present invention is not limited thereto, and the rear sheet 220 may be formed of a transparent material through which sunlight may be incident to implement the double-sided solar cell module 100.

An example of the structure of one solar cell 150 of the plurality of solar cells 150 in this embodiment will be described in detail with reference to FIGS. 3 to 6.

3 is a partial cross-sectional view of a solar cell according to an embodiment of the present invention. For reference, FIG. 3 is a cross-sectional view taken along line III-III of FIG. 4.

Referring to FIG. 3, the solar cell 150 according to the present embodiment includes a semiconductor substrate 110, impurity regions 20 and 30 formed on the semiconductor substrate 110, and impurity regions 20 and 30 or the like. The electrodes 24 and 34 may be electrically connected to the semiconductor substrate 110. The solar cell 150 may include a ribbon 142 electrically connected to the electrodes 24 and 34 to be connected to the neighboring solar cell 150. Here, the semiconductor substrate 110 and the impurity regions 20 and 30 are regions that contribute to photoelectric conversion, and thus may be defined as photoelectric conversion units. The impurity regions 20 and 30 may include an emitter region 20 and a back electric field region 30, and the electrodes 24 and 34 may be first electrodes 24 electrically connected to the emitter region 20. ) And a second electrode 34 electrically connected to the rear electric field region 30. An insulating film, such as an anti-reflection film 22 or a passivation film 32, may be formed on the front and / or rear surfaces of the semiconductor substrate 110. This is explained in more detail.

The semiconductor substrate 110 includes a region where the impurity regions 20 and 30 are formed and a base region 10 that is a portion where the impurity regions 20 and 30 are not formed. The base region 10 may include, for example, silicon containing a first conductivity type impurity. As the silicon, single crystal silicon or polycrystalline silicon may be used, and the first conductivity type impurity may be p type or n type.

When the base region 10 has a p-type, the base region 10 may be formed of single crystal or polycrystalline silicon doped with boron (B), aluminum (Al), gallium (Ga), indium (In), or the like, which are group III elements. Can be done. When the base region 10 has an n-type, the base region 10 is formed of single crystal or polycrystalline silicon doped with phosphorus (P), arsenic (As), bismuth (Bi), antimony (Sb), and the like, which are Group 5 elements. Can be done. The base region 10 may use various materials other than the above-described materials.

Although not illustrated, the front and / or rear surfaces of the semiconductor substrate 110 may be textured to have irregularities in the form of pyramids and the like. If unevenness is formed on the front surface of the semiconductor substrate 110 by such texturing and the surface roughness is increased, the reflectance of light incident through the front surface of the semiconductor substrate 110 may be lowered. Therefore, the amount of light reaching the pn junction formed at the interface between the base region 10 and the emitter region 20 can be increased, thereby minimizing light loss. However, the present invention is not limited thereto, and it is also possible that unevenness due to texturing is not formed on the front and rear surfaces of the semiconductor substrate 110.

An emitter region 20 having a second conductivity type opposite to the base region 10 may be formed on the front side of the semiconductor substrate 110. When the emitter region 20 is n-type, phosphorus, arsenic, bismuth, antimony, or the like may be made of single crystal or polycrystalline silicon, and in the p-type, aluminum (Al), gallium (Ga), indium (In), or the like may be doped. It can be made of monocrystalline or polycrystalline silicon.

In the figure, it is illustrated that the emitter region 20 has a homogeneous structure having a uniform doping concentration as a whole. However, the present invention is not limited thereto. Thus, in another embodiment, emitter region 20 may have a selective structure. In an optional structure, the emitter region 20 may have a high doping concentration and a low resistance in the portion adjacent to the first electrode 24, and may have a low doping concentration and a high resistance in other portions. In addition to the structure of the emitter region 20, various structures may be applied.

In the present exemplary embodiment, the doped region formed by doping the second conductive impurity on the front surface of the semiconductor substrate 110 constitutes the emitter region 20. However, the present invention is not limited thereto, and various modifications are possible, such that the emitter region 20 is formed as a separate layer on the front surface of the semiconductor substrate 110.

The anti-reflection film 22 and the first electrode 24 are formed on the semiconductor substrate 110 and more precisely on the emitter region 20 formed on the semiconductor substrate 110.

The anti-reflection film 22 may be formed on the entire front surface of the semiconductor substrate 110 except for a portion corresponding to the first electrode 24. The anti-reflection film 22 reduces the reflectance of light incident on the front surface of the semiconductor substrate 110 and immobilizes defects existing in the surface or bulk of the emitter region 20.

By decreasing the reflectance of light incident through the front surface of the semiconductor substrate 110, the amount of light reaching the pn junction formed at the interface between the base region 10 and the emitter region 20 may be increased. Accordingly, the short circuit current Isc of the solar cell 150 may be increased. The defect in the emitter region 20 may be immobilized to remove the recombination site of the minority carriers, thereby increasing the open voltage Voc of the solar cell 150. As described above, the open circuit voltage and the short circuit current of the solar cell 150 may be increased by the anti-reflection film 22 to improve the efficiency of the solar cell 150.

The anti-reflection film 22 may be formed of various materials. In one example, the anti-reflection film 22 is any one single film selected from the group consisting of silicon nitride film, silicon nitride film including hydrogen, silicon oxide film, silicon oxide nitride film, aluminum oxide film, MgF ₂ , ZnS, TiO ₂ and CeO ₂ . It may have a multi-layered film structure in which more than one film is combined. However, the present invention is not limited thereto, and the anti-reflection film 22 may include various materials. In addition, a separate front passivation film (not shown) may be further provided between the semiconductor substrate 110 and the anti-reflection film 22 for passivation. This also belongs to the scope of the present invention.

The first electrode 24 is electrically connected to the emitter region 20 through an opening formed in the anti-reflection film 22 (that is, through the anti-reflection film 22). The first electrode 24 may be formed to have various shapes by various materials. The shape of the first electrode 24 will be described later with reference to FIGS. 4 and 5.

The back surface of the semiconductor substrate 110 has the same first conductivity type as the base region 10, but has a back surface field region 30 including the first conductivity type impurities at a higher doping concentration than the base region 10. do.

In the figure, it is illustrated that the back electric field region 30 has a homogeneous structure having a uniform doping concentration as a whole. However, the present invention is not limited thereto. Thus, in another embodiment, the backside field region 30 may have a selective structure. The selective structure may have a high doping concentration and a low resistance in the portion adjacent to the second electrode 34 in the rear field region 30, and may have a low doping concentration and a high resistance in other portions. In another embodiment, the backside field region 30 may have a local structure. In the local structure, the back surface field region 30 may be locally formed only at a portion adjacent to the second electrode 34. In addition to the structure of the rear electric field region 30, various structures may be applied.

In the present exemplary embodiment, the doped region formed by doping the first conductivity type impurities on the rear surface of the semiconductor substrate 110 constitutes the rear electric field region 30. However, the present invention is not limited thereto, and various modifications are possible, such as the rear electric field region 30 being formed as a separate layer on the rear surface of the semiconductor substrate 110.

The passivation film 32 may be formed on the entire rear surface of the semiconductor substrate 110 except for a portion corresponding to the second electrode 34. The passivation film 32 immobilizes defects present in the surface or bulk of the back surface field region 30.

The passivation layer 32 may increase the open voltage Voc of the solar cell 150 by immobilizing defects present in the back surface area 30 to remove recombination sites of minority carriers. As described above, the open circuit voltage of the solar cell 150 may be increased by the passivation layer 32 to improve the efficiency of the solar cell 150.

The passivation film 32 may be formed of various materials. In one example, the passivation film 32 is any one single film selected from the group consisting of silicon nitride film, silicon nitride film including hydrogen, silicon oxide film, silicon oxynitride film, aluminum oxide film, MgF ₂ , ZnS, TiO ₂ and CeO ₂ . It may have a multi-layered film structure in which more than one film is combined. However, the present invention is not limited thereto, and the passivation film 32 may include various materials. In addition, a separate film (not shown) may be further provided between the semiconductor substrate 110 and the passivation film 32 or on the passivation film 32. This also belongs to the scope of the present invention.

The second electrode 34 is electrically connected to the rear field region 30 through an opening formed in the passivation film 32 (ie, through the passivation film 32). The second electrode 34 may be formed to have various shapes by various materials. The shape of the second electrode 34 will be described later with reference to FIG. 6.

A ribbon 142 is positioned on the first electrode 24 to be connected to the second electrode 34 of the neighboring solar cell 150, and another ribbon 142 is positioned on the second electrode 34 so that the other It is connected to the first electrode 24 of the solar cell 150 neighboring toward.

Hereinafter, the structures of the first electrode 24, the second electrode 34, and the ribbon 142 will be described in more detail.

4 is a front plan view of a solar cell according to an exemplary embodiment of the present invention, and FIG. 5 is a front plan view illustrating a first layer and a second layer constituting the first electrode 24 of FIG. 4. Specifically, FIG. 5A illustrates the first layer 241 of the first electrode 24, and FIG. 5B illustrates the first layer 241 and the second layer of the first electrode 24. 242 is shown together.

Referring to FIG. 4, the first electrode 24 of the present exemplary embodiment is formed in a direction intersecting a finger electrode 24a including a plurality of finger electrode portions 242 and a plurality of finger electrode portions 242. At least one busbar electrode 24b is included. In the present embodiment, the busbar electrode 24b includes at least one main part 246 formed in a direction crossing the plurality of finger electrode parts 242 and a protruding part 248 protruding from the main part 240. Include. This is explained in more detail.

The plurality of finger electrode parts 242 of the finger electrode 24a may be disposed in parallel with each other while having the first pitch P1. The width of each finger electrode portion 242 may be 1 μm to 300 μm. If the width of the finger electrode portion 242 is less than 1 μm, it may be difficult to manufacture and the resistance may be high. If the width exceeds 300 μm, the shading loss may increase. In consideration of resistance and shading loss, the width of the finger electrode part 242 may be 30 μm to 120 μm. The first pitch P1 may be 500 μm to 3 mm. Shading loss may increase when the first pitch P1 is less than 500 μm, and it may be difficult to effectively collect the carrier when it exceeds 3 mm. The first pitch P1 may be 1 mm to 2.6 mm for shading loss prevention and efficient collection of carriers. However, the present invention is not limited thereto, and the width and the first pitch P1 of the finger electrode part 242 may be variously modified.

In this embodiment, the finger electrode 24a intersects the finger electrode portion 242 at a position corresponding to the outside of the busbar electrode 24b (more precisely, the protruding portion 248 of the busbar electrode 24b). It may further include an alignment mark portion 244 formed in the direction. The alignment mark portion 244 may be used to align the protruding portion 248 when forming the busbar electrode 24b, which will be described in more detail later. When the finger electrode 24a includes the alignment mark portion 244 as described above, the alignment mark portion 244 is formed in the process of forming the finger electrode 24 to align with the busbar electrode 24b. Can be performed precisely. Thereby, the alignment characteristic of the busbar electrode 24b can be improved, without adding a process.

The bus bar electrode 24b may be formed in a direction crossing the finger electrode part 242 to connect the finger electrode 24a. Only one bus bar electrode 24b may be provided, or as illustrated in FIG. 4, a plurality of bus bar electrodes 24b may be provided while having a second pitch P2 larger than the first pitch P1. In the drawing, one busbar electrode 24b is disposed at the center of the solar cell 150 and two busbar electrodes 24b are arranged to be symmetrical with the busbar electrode 24b positioned at the center. However, the present invention is not limited thereto and various modifications are possible.

In the present embodiment, the bus bar electrode 24b has a first width T1 and a main portion 246 extending in a direction crossing the finger electrode 24a (the longitudinal direction in the drawing) and the main portion ( It may include a protruding portion 248 protruding from the 246 in a direction intersecting with the main portion 246 (for example, a direction parallel to the finger electrode portion 242 (the horizontal direction in the drawing)). Accordingly, the busbar electrode 24b has a second width T2 greater than the first width T1 at the portion where the protruding portion 248 is formed.

Here, the main part 246 is a part designed to attach the ribbon 142 so that the carrier collected by the finger electrode 24a can be transferred to the outside through the ribbon 142.

The main part 246 serves to transfer the carrier collected by the finger electrode 24a to the outside through the ribbon 142 and has a first width T1 larger than the width of the finger electrode 24a. Can be. This makes it possible to easily move the carrier by a low resistance. The first width T1 of the main part 246 may be variously modified, such as being smaller than or smaller than the width of the finger electrode 24a. Therefore, the present invention is not limited thereto.

As such, the main part 246 is a part designed to attach the ribbon 142, so that the first width T1 of the main part 246 and the third width T3 of the ribbon 142 are the same or similar to each other ( Small or large within a certain range). For example, the ratio of the third width T3 of the ribbon 142 to the first width T1 of the main part 246 may be 1: 0.80 to 1: 1.22. When the ratio is less than 1: 0.8, the width of the main portion 246 is much smaller than that of the ribbon 142 so that the anti-reflection film 22 or the emitter region 20 is caused by the ribbon 142 leaving the main portion 246. Can damage. When the ratio exceeds 1: 1.22, the width of the ribbon 142 becomes smaller than the width of the main portion 246 to transfer carriers collected through the busbar electrode 24b to the outside through the ribbon 142. Efficiency may be lowered. The ratio may be 1: 0.90 to 1.11 to more effectively transfer the carrier while effectively preventing damage to the anti-reflection film 22 or emitter region 20. However, the present invention is not limited thereto.

The protruding portion 248 protruding from the main portion 246 is a portion for compensating for the case in which the alignment characteristic of the ribbon 142 is degraded (that is, a misalignment occurs). In addition, a problem such as scratching or cracking occurs during the alignment process, thereby preventing damage to the anti-reflection film 22 or the emitter region 20. This is explained in more detail.

When the misalignment of the ribbon 142 occurs, the ribbon 142 is located at a position deviated from the busbar electrode 24b. The misalignment may be shifted left or right with respect to the ribbon 142, may occur to be inclined with the ribbon 142, or may occur in combination.

When the misalignment of the ribbon 142 occurs as described above, the contact area between the ribbon 142 and the busbar electrode 24b is reduced, thereby increasing the resistance component, thereby increasing the solar cell module (reference numeral 100 of FIG. 1). Output decreases.

In addition, the misaligned ribbon 142 may cause a problem of damaging the solar cell 150. More specifically, with reference to FIG. 1, the solar cell module 100 shown in FIG. 1 is a solar cell having a front substrate 210, a first sealing material 131, and a ribbon 142 formed separately. 150, the second sealing material 132 and the back sheet 220 are laminated and then laminated to manufacture them. However, if a misalignment of the ribbon 142 occurs, the end portion of the ribbon 142 presses a portion where the anti-reflection film 22 or the emitter region 20 is located during the lamination process, thus damaging them by scratching or Cracking occurs. In addition, when the ribbon 142 contacts the finger electrode part 242, the finger electrode part 242 having a relatively thin width may be disconnected by thermal shock or physical shock. This phenomenon is called grid interruption caused by soldering (GICS). The GICS prevents the carrier from being transferred to the busbar electrode 24b while the part of the finger electrode 24a to be connected to the busbar electrode 24b is disconnected. The carrier then moves to another busbar electrode 24b that is located far away, or fails to reach the busbar electrode 24b. Then the output of the solar cell module 100 is reduced.

As described above, the misalignment of the ribbon 142 may greatly affect the performance, efficiency, and the like of the solar cell 150. In this embodiment, the protrusion 248 is formed on the busbar electrode 24b to form the ribbon 142. Even if a misalignment occurs, it is possible to cope with it. That is, even if a misalignment occurs in the ribbon 142, the protruding portion 248 of the bus bar electrode 24 and the ribbon 142 may be in contact with each other. As a result, output reduction of the solar cell module 100 may be compensated.

In this case, the protruding portion 248 may include end protrusions 248a and 248b positioned at the end of the busbar electrode 24b (or the main portion 246). The end portion of the main portion 246 is an area where alignment errors due to misalignment may occur the most. That is, when the misalignment is inclined with respect to the busbar electrode 24b, the largest misalignment occurs at the end of the main part 246. In consideration of this, the protruding portion 248 may be positioned at an end portion of the main portion 246 to effectively compensate for a decrease in contact area between the ribbon 142 and the busbar electrode 24b due to misalignment. In addition, as described above, since the anti-reflection film 22, the emitter region 20, and the finger electrode 24a may be easily damaged at the end portion of the ribbon 142 during the pressing process, the protruding portion 248 at this portion may be damaged. ), The ribbon 142 may be prevented from contacting them even if a misalignment occurs.

More specifically, in the present embodiment, the end protrusions 248a and 248b are formed as opposite positions of the first end protrusion 248a and the first end protrusion 248a which are located at the portion where the end of the ribbon 142 is located. The ribbon 142 may include a second end protrusion 248b that extends and is positioned at a portion extending to the neighboring solar cell 150. As a result, it is possible to effectively cope with a misalignment that may occur at both ends of the busbar electrode 24b. The first and second end protrusions 248a and 248b are symmetrically positioned at both sides with respect to the main part 246, respectively. This effectively compensates for any misalignment occurring on either side. Accordingly, for example, the bus bar electrodes 24b may have an I shape by the end protrusions 248a and 248b and the main part 246. However, the present invention is not limited thereto and various modifications are possible.

Each protruding portion 248 may be formed over at least two of the plurality of finger electrode portions 240. As a result, the protruding portion 248 can be formed while having a sufficient width (width measured in the longitudinal direction of the busbar electrode 24b) W so that it can effectively cope with the misalignment of the ribbon 142. For example, when the protruding portion 248 is formed to correspond to only one finger electrode portion 240, the width W is smaller than the first pitch P1 of the finger electrode portion 240, and thus the ribbon 142 and the ribbon 142. It is difficult to exert the effect of preventing the contact area drop. Thus, the protruding portion 248 may be formed over two or more finger electrode portions 240 so as to have a sufficient width (W). For example, the protruding portion 248 may be formed over two to ten finger electrode portions 240. When formed over more than ten finger electrode portions 240, the width W may become excessively large, thereby increasing the shading loss. Further considering shading loss, the protruding portion 248 may be formed over two to six finger electrode portions 240. Alternatively, the width W of the protruding portion 248 may be 2 mm to 10 mm. If the width W of the protruding portion 248 is less than 2 mm, it may be difficult to effectively cope with the misalignment of the ribbon 142, and if it exceeds 10 mm, the shading loss may increase. Further considering shading loss, the width W of the protruding portion 248 may be 2 mm to 6 mm. However, the present invention is not limited thereto and various modifications are possible.

Here, as described above, the first end protrusion 248a is positioned at one end where the ribbon 142 starts, and the ribbon 142 is a predetermined distance (for example, 2 mm from the end of the semiconductor substrate 110). To 3 mm). In contrast, the portion of the ribbon 142 adjacent to the second end protrusion 248a and extending to the other solar cell 150 is not spaced apart from the semiconductor substrate 110. In consideration of this, the width W of the first end protrusion 248a is equal to or longer than the width W of the second end protrusion 248a, and thus, the width W of the first end protrusion 248a is caused by the ribbon 142 at the portion where the ribbon 142 starts. Damage to the emitter region 20 can be prevented more effectively.

And the protruding length (length measured in the direction crossing the longitudinal direction of the main portion 246) L of each protruding portion 248 (the portion protruding to one side of the main portion 246) is the main portion 246. It may be smaller than the first width T1 of. The protrusion length L may be determined in consideration of tolerances during the alignment process, and the like, since the tolerances during the alignment process generally have a range smaller than the first width T1 of the main part 246. More specifically, the protruding length L of the protruding portion 248 may be 0.1 mm to 0.7 mm. If the protruding length L is less than 0.1 mm, it is difficult to effectively cope with the misalignment of the ribbon 142, and if it exceeds 0.7 mm, the shading loss may increase and may have a value larger than the tolerance of the alignment. However, the present invention is not limited thereto, and various modifications are possible.

As described above, in the present exemplary embodiment, the protruding portion 248 having the predetermined width W and the protruding length L is formed to protrude from the main portion 246. In the portion where the protruding portion 248 is formed by the protruding portion 248, the second width T2 of the bus bar electrode 24b may have a value of 2.1 mm to 3.4 mm. As a result, the second width T2 may be larger than the third width T3 of the ribbon 142. Even if a misalignment occurs as described above, the second width T2 compensates for a decrease in the contact area between the busbar electrode 24b and the ribbon 142 and the emitter region 20 by the ribbon 142. The damage to the anti-reflection film 22 and the finger electrode 24a can be prevented. In the portion where only the main portion 246 is located, the shading loss may be minimized by having the first width W1 smaller than the portion where the protruding portion 248 is disposed.

The first electrode 24 including the finger electrode 24a and the busbar electrode 24b described above may be composed of a single layer or a plurality of layers. In the present exemplary embodiment, the first electrode 24 includes a first layer 240 and a second layer 241 that are sequentially stacked on the semiconductor substrate 110. As such, when the first layer 240 and the second layer 241 are included, the thickness of the first electrode 24 may be sufficiently secured, and the first layer 240 and the second layer may be satisfied to satisfy various desired characteristics. Material, shape, etc. of layer 241 can be optimized.

For example, in the present embodiment, the finger electrode 24a has a two-layer structure including a first layer 240 and a second layer 241, and the busbar electrode 24b includes a second layer 241. It is illustrated having a single layer structure. That is, as shown in FIG. 5A, the first layer 240 is formed to include the finger electrode portion 242 and the alignment mark portion 244 constituting the finger electrode 24a. As shown in (b) of FIG. 2, the second layer 241 may be formed to have the shape of the finger electrode 24a and the busbar electrode 24b. The first layer 240 and the second layer 241 may be formed by various methods. For example, the first layer 240 and the second layer 241 may be formed by printing, deposition, plating, or the like.

Accordingly, the finger electrode 24a, which has a relatively small width and can be formed with a relatively small thickness, may be formed with more layers than the busbar electrode 24b, thereby sufficiently securing the thickness of the finger electrode 24a. For example, the thickness of the finger electrode 24a may be greater than the thickness of the busbar electrode 24b. In addition, the busbar electrode 24b having a relatively large width may be formed in a single layer structure to reduce material costs and the like.

The first layer 201 and the second layer 241 may have the same material or different materials. For example, the first layer 201 may be formed of a material through which fire through occurs by heat treatment, and the second layer 202 may be formed of a material through which fire through does not occur. Then, the finger electrode 24a including the first layer 201 is formed through the anti-reflection film 22, which is an insulating layer, to contact the emitter region 20 to collect carriers of the emitter region 20. Will be. The busbar electrode 24b composed of only the second layer 202 does not penetrate the antireflection film 22 and is positioned on the emitter region 20 with the antireflection film 22 therebetween. Then, the fixed charge characteristic of the anti-reflection film 22 or the passivation film may be maintained at a portion under the busbar electrode 24b to help carrier collection.

However, the present invention is not limited thereto, and the stacked structure of the first electrode 24 may be variously modified.

6 is a rear plan view of a solar cell according to an embodiment of the present invention.

Referring to FIG. 6, in the present exemplary embodiment, the second electrode 34, which is a rear electrode formed on the rear surface of the semiconductor substrate 110, may include a finger electrode 34a and a busbar electrode 34b. At this time, in the present embodiment, the finger electrode 34a of the second electrode 34 may be composed of only the plurality of finger electrode portions 342, and the busbar electrode 34b may be composed of only the main portion 346. The finger electrode portion 342, the main portion 346, and the like are the same as or similar to those described above with respect to the first electrode 24, and thus detailed description thereof will be omitted.

At this time, the width W4 of the main portion 346 may be larger than the third width W3 of the ribbon 142 as a whole. Accordingly, even if a misalignment of the ribbon 142 occurs, it can be sufficiently compensated. In the case of the second electrode 34 disposed on the rear surface of the semiconductor substrate 110, the burden for shading loss is smaller than that of the first electrode 24 located on the front surface, so that the width thereof is larger than the ribbon 142 as a whole. Because it can. As a result, it is possible to effectively cope with the misalignment of the ribbon 142. However, the present invention is not limited thereto, and the second electrode 34 may also have the same structure as that of the first electrode 24 described above, which also belongs to the scope of the present invention. In addition, the second electrode 34 may have various known structures.

As described above, according to the present exemplary embodiment, the structure of the first electrode 24 and / or the second electrode 34 may be improved to improve the structure of the solar cell module 100 that may occur during misalignment of the ribbon 142. It is possible to effectively prevent a decrease in output and damage to the solar cell 150. As a result, the output and reliability of the solar cell module 100 can be improved.

In the above-described embodiment, the bus bar electrode 24b of the first electrode 24 as the front electrode is illustrated to include the protruding portion 248, but the present invention is not limited thereto. At least one busbar electrode 24b, 34b of the first and second electrodes 24, 34 may include a protruding portion 248. Many other variations are possible.

Hereinafter, a solar cell according to other exemplary embodiments of the present invention will be described in detail with reference to FIGS. 7 to 9. Parts that are the same as or similar to those described in the above-described embodiments will not be described in detail, and only different parts will be described in detail.

7 is a front plan view showing a solar cell according to another embodiment of the present invention.

Referring to FIG. 7, the protruding portion 248 of the first electrode 24 of the solar cell 150 according to the present exemplary embodiment may have a main portion between the first end protrusion 248a and the second end protrusion 248b. A central protrusion 248c protruding in the interior region of 246. One or more central protrusions 248c may be provided.

In the present exemplary embodiment, the first end protrusion 248a, the second end protrusion 248b, and the central protrusion 248c may be regularly arranged with a uniform interval therebetween, and may have a uniform size. Here, the uniform interval, uniform size, etc. generally mean an interval, size, etc., which may be regarded as the same interval, size, etc. in consideration of an error, and the like, for example, an interval, size having an error range within 10% And the like. This is to prevent the solar cell 150 from being damaged by the device for attaching the ribbon 142 in the process of attaching the ribbon 142 to the busbar electrode 24b.

More specifically, the ribbon 142 may be bonded onto the busbar electrode 24b by tabbing or the like. At this time, in order to fix the ribbon 142 on the busbar electrode 24b, a plurality of hold pins spaced apart from each other are placed on the ribbon 142 at a predetermined interval, and then between the hold pins. Tabbing can be performed by applying hot air by means of a located nozzle or the like. In this case, an insulating layer, an emitter region, etc. of the solar cell 150 may be damaged by the plurality of hold pins. In consideration of this, in the present exemplary embodiment, the protrusion 248 may be formed to correspond to the gap between the hold pins so as to prevent the hold pins from damaging the solar cell 150 at the part contacting the ribbon 142.

Accordingly, in this embodiment, it is possible to prevent a problem that may occur during the bonding process of the ribbon 142 to effectively prevent damage to the solar cell 150.

8 is a front plan view showing a solar cell according to another embodiment of the present invention.

Referring to FIG. 8, the protruding portion 248 of the first electrode 24 of the solar cell 150 according to the present embodiment is a main portion between the first end protrusion 248a and the second end protrusion 248b. A central protrusion 248c protruding in the interior region of 246. One or more central protrusions 248c may be provided.

At this time, in this embodiment, the protruding length of the central protrusion 248c may be smaller than the protruding length of the end protrusion 248a 248b. When a plurality of central protrusions 248c are provided, the protruding length may be longer as the position is closer to the end protrusions 248a and 248b. That is, the protruding length of the central protrusion 248c located closer to the center portion may be shorter than the central protrusion 248c positioned closer to the end protrusions 248a and 248b. This is considered that when the misalignment of the ribbon 142 is inclined with respect to the busbar electrode 24b, the alignment error is small at the center side and the alignment error is increased at the end side. That is, the protruding lengths of the end protrusions 248a and 248b located at the end side of which the align error is large can be increased to correspond to the misalignment, and the protruding length of the center protrusion 284c located at the center side is relatively small. Shading loss can be minimized while dealing with alignment errors.

 9 is a front plan view showing a solar cell according to another embodiment of the present invention.

9, the protruding portion 248 of the first electrode 24 of the solar cell 150 according to the present embodiment is a main portion between the first end protrusion 248a and the second end protrusion 248b. A central protrusion 248c protruding in the interior region of 246. One or more central protrusions 248c may be provided.

At this time, in the present embodiment, the central protrusion 248c may be disposed at various intervals while having a different width from the first and second end protrusions 248a and 248b. As such, the arrangement of the protruding portions 248 may be variously modified.

Features, structures, effects, and the like as described above are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. In addition, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified with respect to other embodiments by those skilled in the art to which the embodiments belong. Therefore, contents related to such combinations and modifications should be construed as being included in the scope of the present invention.

150: solar cell
24: first electrode
24a: finger electrode
242: finger electrode portion
244: alignment mark
24b: busbar electrode
246: main part
248: protrusion
34: second electrode

Claims (20)

Photoelectric conversion unit; And
First and second electrodes connected to the photoelectric converter
Including,
The first electrode may include a bus electrode including at least one finger electrode including a plurality of finger electrode parts, a main part formed in a direction crossing the plurality of finger electrode parts, and a protruding part protruding from the main part. Including,
The protruding portion is formed over at least two of the plurality of finger electrode portions,
The finger electrode is formed in a direction crossing the finger electrode part at a position corresponding to the outer edge of the protruding portion to align the protruding portion for preventing misalignment of the conductive ribbon connected to the first electrode. The solar cell further including an alignment mark part. The method of claim 1,
And a protruding length of the protruding portion is smaller than the width of the main portion. The method of claim 1,
The protruding length of the protruding portion is 0.1mm to 0.7mm. The method of claim 1,
A solar cell having a width of the protruding portion of 2 mm to 10 mm. The method of claim 1,
And the protruding portion is formed over two to ten of the plurality of finger electrode portions. The method of claim 1,
The bus bar electrode has a width of 2.1mm to 3.4mm at the portion where the protruding portion is located. The method of claim 1,
And a protruding end portion wherein the protruding portion is positioned at an end of the main portion. The method of claim 7, wherein
The end protrusion is positioned symmetrically on both sides with respect to the main portion. The method of claim 7, wherein
The conductive ribbon has one end positioned above the busbar electrode, the other side extending to a neighboring solar cell,
The end protrusion includes a first end protrusion adjacent to the one end and a second end protrusion positioned at a position opposite to the first end protrusion,
The solar cell of claim 1, wherein the width of the first end protrusion is equal to or greater than the width of the second end protrusion. The method of claim 7, wherein
And a central protrusion in which the protruding portion protrudes from an inner region of the main portion. The method of claim 10,
And a protruding length of the central protrusion is smaller than a protruding length of the end protrusion. The method of claim 10,
And the center protrusion and the end protrusion are arranged regularly at equal intervals. The method of claim 1,
And a bus bar electrode having a width greater than a width of the conductive ribbon at a portion where the protruding portion is located. The method of claim 13,
Width of the ribbon: the width ratio of the busbar electrode in the portion where the main portion is located 1: 0.80 to 1: 1.22 solar cell. delete The method of claim 1,
The photoelectric conversion unit includes a semiconductor substrate and an emitter region,
Further comprising an insulating film formed on the emitter region,
The finger electrode is formed to penetrate the insulating film to contact the emitter region,
The bus bar electrode is formed on the insulating film. The method of claim 1,
The finger electrode has a two-layer structure including a first layer positioned on the photoelectric converter and a second layer positioned on the first layer,
The busbar electrode has a single layer structure having the same material and thickness as the second layer. The method of claim 17,
The solar cell of claim 1, wherein the first layer and the second layer have different materials. The method of claim 1,
Further comprising another conductive ribbon connected to the second electrode,
And the second electrode as a whole has a width greater than that of the another conductive ribbon. Photoelectric conversion unit; And
First and second electrodes connected to the photoelectric converter
Including,
The first electrode may include a finger electrode including a plurality of finger electrode portions, and a bus bar electrode including at least one main portion formed in a direction crossing the plurality of finger electrodes and a protruding portion protruding from the main portion. and,
The width of the bus bar electrode at the portion where the protruding portion is located is 2.1mm to 3.4mm,
The finger electrode is formed in a direction crossing the finger electrode part at a position corresponding to the outer edge of the protruding portion to align the protruding portion for preventing misalignment of the conductive ribbon connected to the first electrode. The solar cell further including an alignment mark part.

Images